#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUF_SIZE 100

void read_childproc(int sig)
{
    pid_t pid;
    int status;
    pid = waitpid(-1, &status, WNOHANG);
    printf("终止子进程 id : %d\n", pid);
}

int main(int argc, char *argv[])
{
    int serv_sock, clnt_sock;
    struct sockaddr_in serv_addr, clnt_addr;
    int fds[2];

    pid_t pid;
    struct sigaction act;
    socklen_t addr_size;
    size_t str_len;
    int state;
    char buf[BUF_SIZE];

    act.sa_handler = read_childproc;
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    state = sigaction(SIGCHLD, &act, 0);

    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = PF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons((uint16_t)atoi(argv[1]));

    bind(serv_sock, (const struct sockaddr *)&serv_addr, sizeof(serv_addr));
    listen(serv_sock, 5);

    pipe(fds);
    pid = fork();
    if(pid == 0) {
        FILE *fp = fopen("echomsg.txt", "wt");
        char msgbuf[BUF_SIZE];
        size_t len;
        for(int i = 0;i < 10;++i) {
            len = (size_t)read(fds[0], msgbuf, BUF_SIZE);
            fwrite((void *)msgbuf, 1, len, fp);
        }
        fclose(fp);
        return 0;
    }

    while(1) {
        addr_size = sizeof(clnt_addr);
        clnt_sock = accept(serv_sock, (struct sockaddr *)&clnt_addr, &addr_size);
        if(clnt_sock == -1) {
            continue;
        } else {
            puts("新的客户端连接了");
        }
        pid = fork();
        if(pid == 0) {
            close(serv_sock);
            while((str_len = read(clnt_sock, buf, BUF_SIZE)) != 0) {
                write(clnt_sock, buf, str_len);
                write(fds[1], buf, str_len);
            }
            close(clnt_sock);
            puts("客户端断开连接");
            return 0;
        } else {
            close(clnt_sock);
        }
    }
    close(serv_sock);
    return 0;
}
